Control of delamination in contoured laminated structures

ABSTRACT

A structural element made of a high impact sheet material, a resilient, semi-flexible core material, and a plurality of independent, preformed parallely-spaced rib members extending substantially across the width of said sheet material and fixedly attached thereto by an adhesive with said sheet material being flat, said plurality of rib members having adjacent, confronting side surfaces substantially parallel to one another, the forces created by bending of the structural element producing fractional detachment between at least some of said rib members and said sheet material being controlled by the width and height of said rib members and the distance between adjacent rib members and thereby determining the limit of bending of said structural element, thereby enabling a smooth surface of said high impact sheet material by preventing ripples and ridge lines therein with the bending of said structural element.

This application is a continuation application of application Ser. No.08/174,318, filed 30 Dec. 1993 now U.S. Pat. No. 5,618,601.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods for controlling the delaminationwithin contoured laminated structures and to the structures for carryingout such methods, and more particularly to such methods and structuresfor limiting or preventing delamination within laminated structurescomprising at least one facing laminate and a plurality of spaced ribsattached thereto, and that is either adapted to be configured into acurved shape, thereby maintaining a desired appearance of the laminatedstructure, or remains in a flat, non-distorted condition to be used tocover a flat surface area.

2. Related Art

The development and subsequent proliferation of high impact decorativesurface materials has prompted many changes in the cabinet andarchitectural industry. These changes included new adhesives, tools,fasteners and assembly techniques. The substrate cores of choice forlamination are composition board for flat panels and papers or plywoodfor contours.

In most cases, the flat, average size panels are easy to laminate,handle and assemble and are relatively stable. This is not the case whenusing large panels, contours or closed loop designs. Although manydecorative surface materials are durable and flexible, most fabricatorsare reluctant to produce contoured structures because rigid contouredcomponents are not compatible with flat-line production systems andrequire special hands-on labor, intensive handling, laminating andassembly methods.

As an additional deterrent to the use of such panel structures is thatall of the wood base cores expand and contract in response to theatmosphere at different rates of movement than the surface sheet. Thisdynamic tension is potentially damaging to the surface sheet and glueline or both.

Laminated strips, including at least an outer surface strip havingscuff-resistance characteristics, for example, and a desired eye appeal,and a core material, are formed over partially or fully curvedstructural surfaces such as columns, pillars, kitchen counters, etc.,and permanently retained by the use of an adhesive between the innersurface of the laminated strip and the structural surface. Thedeformation of the laminated strip to form the desired contour shapeproduces stresses and strains tending to distort the laminated strip,separating it from the structural surface--a process called leverageddelamination. These forces and stresses are primarily caused by a leverand fulcrum action resulting from the bending of the laminated strip toconform to the structural surface, although changes in temperature andhumidity are also contributing factors in the build-up of structuralstress. Such delamination degrades the surface appearance of thelaminated strip and may even adversely affect the adhesion of thelaminated strip to the structural surface depending on the severity ofthe forces causing the delamination. The forces and stresses causingdelamination increase with the degree of bending of the laminated stripto conform it to the shape of the structural surface.

The phenomena of delamination is determined by parameters such as thestrength of the adhesive, the laminated strip and the structuralsurface. If the laminated strip is weaker than the adhesive, forexample, the laminated strip will distort or tear before delaminationoccurs. However, if the adhesive is weak, then delamination will occurbefore distortion or tearing of the laminated strip. It is thusobviously desirable to design the laminated strip and select theadhesive to provide a controlled delamination of the laminated strip toprevent distortion or damage thereto.

U.S. Pat. No. 5,232,762, issued to the same inventor as the subjectapplication, relates to a structural element for initial, substantiallyflat attachment to the surfaces of high impact sheet materials, andadapted for attachment to curved surfaces and includes a firstresilient, semi-flexible, sheet material having a given length andwidth; a second, flexible sheet material of substantially the same widthas the first sheet material; a plurality of parallely-spaced,independent preformed rib members sandwiched between the first andsecond sheet material and each rib member extending substantially acrossthe width of the first and second sheet material and fixedly attached toboth the first and second sheet material by an adhesive with the firstand second sheet material being flat, the width and height of thepreformed rib members and the distance between adjacent rib membersdetermining the limit of bending of the first or second sheet material;and at least one of the first and second sheet material being shearable,thereby enabling areas and the degree of bending within the areas of thefirst and second sheet material to be determined by the selectivecutting of only the at least one sheet in the spaces formed between theplurality of rib members. In an alternative embodiment only one sheet offlexible mateiral is used and the bending of the structural element isdetermined solely by the spacing between the rib members and theirheight and width.

U.S. Pat. No. 4,536,427 relates to laminated contoured structures inwhich the yieldability of the adhesive material between a facing sheetand the core material enables "contouring" of the laminated structure.The adhesive used remains pliable or toffee-like to allow the necessaryseparation between the scrim and the core.

U.S. Pat. No. 3,540,967 discloses contour-core structures in which theadhesive material between a scrim and the core is dislodged to enablethe structure to conform to a curved-shape surface.

Controlling the properties of the adhesive is also an important factorin preventing "telegraphing" or the creation of flex lines or crackingin the laminated strip. Too strong an adhesive preventing delaminationresults in such cracking or the creation of flux lines in the outersurface of the laminated strip.

Thus, it is desirable to control the delamination of the adhesive fromthe structural surface and/or control the delamination of the laminatedstructure from the adhesive in order to prevent the aforementionedproblems from occurring. As is evident from the above discussion, priorattempts to achieve controlled delamination rely entirely on theselection of a proper adhesive. Very little consideration has been givento the flexibility of the laminated strip itself in controlling thedelamination of the laminated strip from the structural surface.

SUMMARY OF THE INVENTION

KERFKORE is a registered trademark pertaining to laminate structures ofthe type described herein and is owned by the same inventor as thepresent application.

The KERFKORE structure of the invention can be uniformly laminated,milled and drilled using flat-line mass production machines and storedflat for later selective constrained cold forming of core and surfacesheet simultaneously into stabilized contoured panel elements suitablefor attachment to "coreless" type cabinet and architectural framing.

The basic structure of the invention comprises a structural element forattachment to curved surfaces in which a plurality of parallely-spaced,independently preformed rib members are sandwiched between at least two,first and second sheet material members; with the rib members extendingsubstantially across the width of the first and second sheet materialmembers and fixedly attached to both the first and second sheet materialmembers by adhesive material with the structure being flat, the widthand height of the preformed rib members, the distance between adjacentrib members and the strength of the adhesive determining the limit ofbending of the first and second sheet material members. At least one ofthe first and second sheet members being shearable, thereby enablingareas and the degree of bending within said areas of the first or secondsheet material to be determined by the selective cutting of only one ofthe at least one sheet in the spaces formed between the plurality of ribmembers.

An alternate manner of describing the laminate structure of theinvention is to define it as being a pliantly diffusive, compositestructure formed of an initially flat, selectively flexible compositestructure disposed for pliantly, spontaneous, fractional, intermittentdiffusion and comprising a surface sheet of high impact, semi-rigidmaterial bonded flat to a diffuse, segmented plurality of structuralmaterial extending substantially across the expanse of the surface sheetmaterial with the segments being spaced and sized in a pattern renderingtenuous the otherwise permanent flat bond against flexing tensions ofthe surface sheet material and limiting the surface sheet flexing angleof interference to minus 20 degrees between adjacent segments in atleast one direction, the flexing of the complete assemblage resultant infractional intermittent detachment between elements of the compositestructure, thus dispersing potentially damaging concentrations of stressand preserving the structural integrity and smooth visual continuity ofthe originally flat composite structure either in repititous flexingmotion as a curved sliding door or in a fixed position as a contouredstructure.

A primary object of the present invention is to control the delaminationof a flat laminated structure (basically as defined above) caused bybending to be conformed into the curved contour of a structural surfaceby increasing the flexibility of the laminated strip structure to reducethe stresses and forces tending to induce the delamination.

Another object of the invention is to provide both a course and a fineadjustment of the bendability of the laminated strip by varying the sizeand spacing of the ribs in the core of the laminated strip to obtain acourse bendability adjustment, and to provide severable connecting ribswithin the rib elements for obtaining a fine bendability adjustment ofthe laminated strip.

It is a further object of the invention to provide a method andstructure for obtaining a selectable, variable bendability adjustment ofthe laminated strip by selectively scoring a laminated sheet of thelaminated strip between the spaced ribs.

Yet another object of the invention is to provide a method and structurefor controlling delamination in laminated structures as disclosed hereinby using a compressed latex paper scrim between the facing laminate ofthe laminated structure and the structural surface to absorb certain ofthe stresses and forces causing delamination to aid in obtaining thedesired contour of the laminated structure.

And still another object of the invention is to provide variable-widthscoring of a backing sheet in the laminated sheet structure inconjunction with the size and spacing of the ribs in the core structureof the laminated strip to control delamination.

Another purpose of this invention is to provide a group of structuralsubstrate reinforcement cores of different cross-sections but similarpurpose when in bonded combination with high impact surfacing materialssuch as, high pressure laminates, sheet metals and the like suitable forattachment to cabinet and architectureal framing or as self-contained,closed loop, monoformed structures engineered to be instrinsicallysubservient to and dynamically influenced by said surface sheets at restin the initial flat condition, in mechanically forced motion, under thesustained stress of curved configurations, or atmospherically induceddimensional changes.

Imperative to the feasibility and functionality of laminated corestructures such as described herein, there is the control of theperpetual dynamic tension between the essential elements contained inlaminated components, core, adhesives and the surface sheet(s).

When tenuously bonded to surface sheet the core maintains permanentdynamic equilibrium between the three elements.

A flat and unstressed core produces impalpable adjustments dictated bythe surface sheet due to atmospheric changes.

When the flat core sheet is moved from a flat condition to a contouredcondition, there is a mechanical lever and fulcrum effect that tends topeel the surface sheet away from portions of the segments to disposeconcentrations of stress, which action can be designated as leverageddelaminations.

The conventional method of producing grooved or mitered panels comprisestwo phases, namely, (1) simply bond the flexible sheet to an unmilledpanel and (2) cut completely through to the sheet in "one pass". Thecutters are usually pointed and adjusted to lightly score the sheet(especially if it is metal) to weaken and define each ply point.

The objective in producing KERFKORE is to avoid weakening, or in any wayscoring, the sheet facing material at the flex point area.

To eliminate the damaging effect from the close proximity of the cuttersto the sheet and to reduce flex point gap variations due to worncutters, the raw panel is partially scored in one pass before laminatingand then cut through on a second pass after laminating.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, features and advantages of the invention are readilyapparent from the following description of preferred embodiments of thebest mode of carrying out the invention when taken in conjunction withthe following drawings, wherein:

FIG. 1 shows a plurality of rib members adhered to a facing sheet withsuitable spacing to control delamination in a basic laminated structurein accordance with the present invention;

FIGS. 2a and 2b shown the various causes and effects of delaminationbetween the rib and laminate facing sheet of a laminate structure;

FIG. 3a illustrates the use of a compressed latex paper scrim betweenthe laminate-sheet-facing material and the spaced ribs to obtaindelamination control in accordance with the present invention; FIG. 3bis an enlarged view of a section of a laminate constructed in accordancewith the invention illustrating the principle of leveraged delamination;FIG. 3c is another enlarged view of a laminate constructed in accordancewith the invention illustrating the principle of leveraged delaminationwith a doubly bent or compund bent laminate; FIG. 3d is a modifiedembodiment in which the laminate includes alternately-directed throughcuts as a means of controlling the delamination of the laminatestructure; and FIG. 3e is a further modified embodiment in which thelaminate includes alternately-reverse-directed through cuts as a meansof controlling the delamination of the laminate structure;

FIG. 4 is a cross-sectional view of a laminate structure showing the ribconnectors between adjacent ribs forming the core of a laminatestructure for obtaining a fine adjustment of the bendabilitycharacteristic of the laminate structure in accordance with theinvention;

FIG. 5 illustrates the manner in which a laminate sheet in the laminatestructure can be scored to alter the bendability characteristic of thelaminate structure to control contouring of the laminated core structurein accordance with the present invention;

FIG. 6a is an exploded cross-sectional side view of a laminate structurein accordance with one embodiment of the invention illustrating atriangularly-shaped notch; and FIG. 6b is a cross section of thestructure of FIG. 6a;

FIG. 7a is an exemplary embodiment of a multiple web KERFKORE sheet andFIG. 7b shows a detail of the sheet structure; FIG. 7c is anotherexemplary embodiment of the invention showing a multi-layered webstructure; and FIG. 7d illustrates the manner in which the webs arescored to enable the multi-layered structure to bend; and

FIG. 8a shows a laminated structure in accordance with the invention inwhich the structure is reversible depending upon the size of the radiusof the bend and which can accommodate an accessory attachment; and FIG.8b illustrates the use of the accessory attachment.

DETAILED DESCRIPTION

The basic construction of a sublaminate structure which is used to formlaminate structures in accordance with the invention is shown in FIG.1a. As shown in FIG. 1a, the plurality of rib members 20 are attached toa high impact laminate-facing-sheet 22 by a suitable adhesive to form aflat sublaminate structure 24. Sublaminate structure 24 is intended tobe used in both a flat or a curved configuration, i.e. to be fastened toan essentially flat surface or to be bent to conform to a curved surfaceso that in both instances the laminate structure forms a facingproviding a smooth desired appearance having high resistance to beinggouged, marred or otherwise damaged. The width w, height h and spacing sof the rib members 20 are all factors determining the upper limit ofbending of the sublaminate structure 24 where that structure is to beused to conform to a curved surface.

Additional factors controlling the degree of bending of the laminatestructure 24 are the flexibility of the high impactlaminate-facing-sheet member 22 and the strength of the adhesive used toattach the plurality of rib members 20 to the laminate-facing-sheetmember.

For the purposes of the invention, it is assumed that one of ordinaryskill in the art will recognize that it is necessary that theflexibility of the laminated-facing-sheet material 22 must be such thatit can be bent to the maximum radius without producing any distortion inthe appearance of the laminate-facing-sheet material such as would occurby cracking, telegraphing or actual severance of the laminate facingsheet from the substrate. The laminate structures in accordance with theinvention are capable of being bent with at least a three inch radius.

Thus the factors affecting the bendability of a laminate sheet-facingmaterial in accordance with the invention are the height h and width wof the rib elements 20, the spacing s between the rib elements and theadhesion between the rib members 20 and the facing-sheet 22. Theadhesion between the rib members 20 and the facing-sheet 22 is in turndetermined by the strength of the adhesive used to attach the ribmembers to the facing-sheet and the leverage applied by the bending ofthe facing-sheet 22 to the adhesive and the rib members.

The spacing s between the rib members 20 and the height h of the ribmembers are selected to accommodate the maximum bending radius necessaryfor the particular application of the laminate structure 24. It isapparent that the greater the height h and the width w of the ribmembers 20 the greater must the spacing s be between the adjacent ribmembers.

It is also apparent that the greater the width w of the rib members 20,the greater will be the leverage force applied by the sheet-facingmaterial 22 to delaminate or separate the rib members from thesheet-facing material 20 for any given radius of bending of thesublaminate structure 24. Moreover, the greater the radius r of bendingof the sublaminate structure 24, the greater will be the leverage forcetending to delaminate or separate the rib members 20 from thesheet-facing material 22 for any given width w of the rib members.Furthermore, for any given width w of the rib members 20 and the radiusr of bending of the sublaminate structure 24, the strength of theadhesive bonding between the rib members 20 and the sheet-facingmaterial 22 will determine the delamination of the rib members from thesheet-facing material. Thus, the adhesive bonding must not exceed thefracture strength of the sheet-facing material, thereby enabling acontrolled delamination to occur so that the basic sublaminate structure24 can be bent to the desired radius without fracturing the surfacesheet-facing material 22. Also, the adhesion bond must be of sufficientstrength to enable the rib members 20 outside the area of bending of thesheet-facing material 22 to remain bonded thereto.

However, for purposes of describing the practical limits of the maximumbending radius R, it is more convenient to define the maximum bendingradius R as a function of the angle between adjacent rib members withrespect to the thickness of the rib members as shown in Examples I, IIand III below as opposed to defining a great number of relationshipsbetween the spacing s, height h and width w of the rib members.

As shown in Example I, with a 13/4" height h of the rib members it ispractical to obtain an approximate maximum angle of 5 degrees betweenadjacent rib members at the point of maximum bending of the laminatesubstrate. In Example II, with a rib member height h of 7/8" a range ofbetween 6-12 degrees angle between the adjacent rib members is possible.Finally, in Example III with a rib member height h of 7/16" anapproximate maximum angle of 17 degrees between adjacent rib members ispossible.

It will be apparent to those skilled in the art of laminated structuresthat other relationships between these parameters will produce laminatedstructures in accordance with the invention.

The various structural causes and effects of controlling delaminationbetween the rib and laminated-sheet facing material of a basicsublaminate structure generally of the type used in the invention areillustrated in FIGS. 2a and 2b for the purpose of demonstrating thefactors affecting delamination. FIG. 1a illustrates a desireddelamination of the rib member 20 from the facing sheet material 22 ascaused by the leverage produced between the ends of the rib member bycurvature of the sheet-facing material to a desired radius. A space 23is produced by the separation of the rib member 20 from the sheet-facingmaterial 22; however, the rib member remains attached, or at least inabutting relationship at end portions 21, with the sheet-facingmaterial. In the event that the radius of bending of the sublaminatestructure 24 is greater than that shown in FIG. 1a, it is desirable thatdelamination occur between several rib members 20 and the sheet facingmaterial 22 with contact remaining at the outer edges of the delaminatedrib members and the sheet-facing material.

FIG. 1b illustrates an instance in which improper delamination hasoccurred whereby the sheet-facing material 22 remains attached to therib member 20 in an area between two delaminated areas 19. Such improperdelamination most likely results from a too flexible sheet-facingmaterial 22 accompanied by the use of too strong an adhesive, therebyenabling a fracture 25 to occur in the sheet-facing material.

The controlled delamination techniques of the present invention enable awider variation in the constraints placed on the height h, width w andspacing s parameters as discussed above. For example, it is apparent asshown in FIG. 2a that if the spacing s is too narrow for the degree ofbending (radius r ) the respective edges 26, 27 of adjoining rib members20 will abut prior to the completion of the bending of the sublaminatestructure 24 so that increased delamination pressure will be applied tothe adhesion between the rib member(s) 20 and the sheet facing material22. This will cause additional delamination between the rib member(s) 20and the sheet-facing material 22.

To enable such delamination to occur without damage to either the ribmembers 20 or the sheet facing material 22, it is readily apparent thatthe adhesive bond between the rib members and the surface sheet-facingmaterial 22 must be of less strength than the fracture or shearingstrength of either the rib members or the sheet facing material. In thecase where the sublaminate structure 24 includes only an adhesivebetween the rib members 20 and the sheet facing material 22, only thestrength of the adhesive is available as the factor controlling thedelamination (assuming a given rib member, sheet-facing material, andwidth w, height h and spacing s between the rib members).

However, in accordance with another embodiment of the invention, thebasic sublaminate structure 24 illustrated in FIG. 1a may be modified toinclude a backing web member between the plurality of rib members andthe sheet-facing material as shown in FIG. 3a. As illustrated in FIG. 3aa compressed latex paper scrim 30 is formed between sheet-facingmaterial 22 and rib members 20 with the adhesive 32 bonding the scrim 30to the individual rib members 20. Thus when the modified sublaminatestructure 24' is bent to form a given radius r, the scrim 30 separatesfrom the sheet facing material 22 to provide the controlled delaminationnecessary to enable the sublaminate structure 24' to achieve the desiredbending radius as shown at areas 33, 34 between the affected adjacentrib members 20 and in the delamination control area 35. In areas 33, 34the scrim 30 laterally yields to the changing dimensions of the sheetfacing material 22 caused by the bending radius r. To obtain this resultthe adhesion between the scrim 30 and the sheet-facing material 20 mustbe less than the adhesion between the scrim 30 and the plurality of ribmembers 20.

The practical effect of this embodiment of the invention is that theconstraints on the strength of the adhesive bond between thesheet-facing material 22 and the rib members is divided, therebyenabling the adhesion between the scrim 30 and the rib members 22 to bedifferent than that between the sheet-facing material 22 and the scrim30. This affords a greater flexibility in the selection of the adhesivesthan with the first embodiment of FIG. 1 without the scrim and whereinthere is only one adhesive. Therefore, the adhesive strength isdetermined by the different adhesion between the adhesive and thesheet-facing material and the adhesion between the adhesive and theindividual rib members.

FIG. 3b represents an enlarged view of a cross section of a laminatesubstrate in accordance with the invention and illustrating leveragingaction of the surface sheet 22' along the contacting surface 23 betweenthe surface sheet 22' and the rib member 20' which produces a maximumstress point at the edge 25 of the rib member which stress is controlledby the angle of interference 27 between adjacent rib members 20' asshown in the drawing. It is apparent that the larger the angle ofinterference 27 the larger the maximum stress that is produced to causedelamination of the laminate substrate.

FIG. 3c illustrates the two different types of delamination produced ina laminate substrate according to the invention and which is subjectedto a double bending moment such that delamination is produced in thecenter of a rib member 20" with compressive forces existing at eachcorner 25" of the rib member 20". At the right hand side of the laminatestructure delamination occurs at each corner 29 of the rib member 20"with a compressive force existing in the middle of the rib member 20".Thus, the location of the compressive forces enables the laminatesubstrate to endure a reverse bending as illustrated in the Figure.

FIG. 3d illustrates a modified embodiment of the laminate substrate ofthe invention in which the rib member 20'" is a core material in whichalternate through cuts are made to enable the laminate substrate to becontoured and wherein the delamination effects are just the opposite ofthose previously described with respect to FIGS. 3b and 3c. As seen inFIG. 3d, the delamination occurs in a space 33 opposite a through cut onthe opposite side of the laminate and between the through cuts which areinvolved in producing the bending of the laminate substrate.

FIG. 3e illustrates a further embodiment of the invention whichrepresents a modification of the embodiment shown in FIG. 3d. The ribmember 20"" is a core material in which the alternate through cuts aremade opposite to that shown in FIG. 3d and wherein the delaminationoccurs in a space 33', approximately in the middle of a rib member. Theintermediate cuts 34 provide bi-level bend radii; and primary andsecondary flex points 35 and 36 are respectively provided. Thismodification provides more flex points per linear measure withoutreducing the bonding surface and requires less delamination by allowingthe rib members to camber between primary flex points and thus maintainmore contact with the surface sheet.

In a further modified embodiment of the invention as shown in FIG. 4,the sublaminate structure 24 of FIG. 1 is modified by including webbing40 between adjacent rib members 20, which webbing decreases theflexibility or bending of the thus formed sublaminate structure 24". Theflexibility of the sublaminate structure 24" can be selectivelyincreased by selectively severing particular webs 40 between the ribmembers in those areas where bending of the sublaminate structure isrequired in accordance with the manner in which the sublaminatestructure is to be conformed to a curved shape. In FIG. 4 the webs 40are shown at approximately the midpoints of the rib members 20. However,it is understood that the webs 40 may be formed at other regions of therib members to alter the flexible characteristics of the sublaminatestructure 24".

In a preferred embodiment of the invention as shown in FIG. 5, thelaminate structure of FIG. 1 includes a backing member 42 which includesscored sections 44 between adjacent rib members 20. The bendability ofthe thus formed sublaminate structure 24a is determined by severing thebacking member 42 at selected scored sections 44 as shown at regions 46to obtain the desired flexibility of the sublaminate structure to bebent into a desired curved shape. This preferred embodiment of theinvention may further be modified by including the web-linked rib memberstructure of FIG. 4 as the basic rib element instead of the individualrib member structure of FIG. 1. In FIG. 5, the severed sections 44include bent-in portions 48 of the backing member 42 which limits thebendability of the laminate structure as that structure is bent to adesired radius.

The embodiment of FIG. 5 may also be modified to increase thebendability of the laminate structure 24a by multiple cutting of thescored sections 44 to increase the width of the selected scoredsections. An increased cut width may also be obtained by using a widercutting implement. The increased cut width of the scored sectionsenables the laminate structure 24a to bend to a greater extent than witha narrower cut width.

In a further embodiment of the invention illustrated in FIG. 7a, thelaminate structure 24b comprises a high-impact surface sheet, a latextype paper strip 52 attached by adhesive 54 to the surface sheet andsandwiched between the surface sheet 50 and a flexible core material 56which includes cutout sections 58 having notched portions 60 each havinga peak portion 62 around which the latex type paper strip extends asshown in FIG. 6a. The substrate 24b is completed with a backer sheet 64preventing bending of the substrate 24b unless the backing sheet 64 iscut as shown in FIG. 6b at portions 66.

The notched portions 60 enable the laminate substrate 24b to bend atpeaked portions 62 at which portions the latex type paper 52 iscompressed as indicated at 66. During bending of the laminate substrate24b, the surface sheet 50, adhesive 54 and latex type paper 56 expand asindicated at 68. The same components of the laminates substrate 24bundergo compression as indicated at 70.

As indicated in FIG. 6b by forces 72, 74 applied to the laminatesubstrate beyond the area of cutout portions 66 of backer sheet 64, thelaminate substrate 24b will tend to bend in a downward direction to forma desired bend radius. The cutout portions may be formed by simplycutting the backing sheet to remove the necessary portion of the backingsheet 64.

FIG. 7a illustrates a modified embodiment of that described above withrespect to FIG. 4 and involves the addition of a backing sheet 76 to theopposite side of the laminate substrate 24c to which the surface sheet22 is attached. A flexible laminate substrate is formed at desiredlocations by selectively cutting web sections 40 and the associatedportion of the backing sheet 76 as indicated at 78 and 80, respectively.

FIGS. 7c and 7d illustrate the manner in which sublaminate substratesindividually formed of rib members 82, 82' and 82" and a backing sheet84, 84' and 84", respectively are stacked on top of one another andattached by an adhesive between a respective backing sheet and theadjacent rib member to form a sublaminate structure 24d. A surface sheet86 is bonded to the top of sublaminate substrate 24d and the resultinglaminate substrate 88 is made flexible by cutting through the backingsheets 84, 84' and 84" as illustrated in FIG. 7d at portions 90, 92 and94.

In the modified embodiment of the invention shown in FIG. 8a asublaminate structure 24e is formed of rib members each having a notch98 formed on each side of the rib member and the rib members 96 areattached or bonded to a backing sheet 100. An accessory attachment 102in the form of an "H" includes opposed gripping edges 103 at each end ofthe legs of the "H" as shown in FIG. 8a. The sublaminate structure 24eis then provided with a surface sheet (not shown) bonded either over thebacking sheet 100 or attached to cover the open ends of the rib membersopposite the backing sheet. With the backing sheet attached tosublaminate structure 24e over the backing sheet 100 the flexibility ofthe resultant laminate substrate is limited so that it will bend in asmaller radius than will the resultant laminate substrate formed withthe surface sheet over the sublaminate substrate 24e opposite thebacking sheet 100. In the latter circumstance, the bendability of thelaminate substrate is obtained by severing the backing sheet alongselected sections 104 between the rib members 96, as described abovewith respect to the embodiment of the invention disclosed in FIG. 5. Inthe former circumstance, the flexibility of the laminate structure isprovided by the separation between the rib members as discussed abovewith respect to the embodiments of the invention disclosed in FIGS. 1and 4.

In the embodiment of FIG. 8a wherein the surface sheet is applied to thesublaminate structure 24e opposite the backing sheet 100, accessory 102may be attached to the offset projections 106 on each of rib members 96by cutting through the backing sheet 100 along the associated severanceregions 104 and passing the appropriate end of the attachment 102 intoengagement with the desired rib member 96.

As shown in FIG. 8b, two sublaminate structures 24e' and 24e" may beattached together via the engagement of engagement projections 103' withsevered web members 106, 108. In this embodiment it is understood thatsublaminate structure 24e is attached to attachment 102 shown in FIG.8b.

The embodiments of the invention described herein are intended for thepurpose of illustrating the structure and function of the invention.Those skilled in the art of facing structures will recognize that theembodiments described herein are capable of modification and thus thescope of invention described herein is not to be limited to the specificexemplary embodiments of the invention described, but the scope of theinvention is to be determined by the claims appended hereto and theequivalents to which the claimed structures are entitled.

What is claimed is:
 1. A composite structural material having an outersurface for surface-covering applications, comprising:a sheet materialhaving an outer surface and an opposing inner surface; a plurality ofparallely-spaced rib members extending substantially across the width ofsaid sheet material on the opposing inner surface and attached theretoby an adhesive with said sheet material being substantially flat; theadhesive bond between the sheet material and the rib members being suchthat when the structural member is bent a self detachment of the sheetmaterial from at least some of said rib members occurs allowing thesheet material to form a smooth curved shape devoid of ridges or planes;and a backing sheet attached to the opposite side of said rib membersthan said sheet material, and the flexibility of the compositestructural material is altered by said backing sheet being cut betweenadjacent rib members.
 2. A composite structural material having an outersurface for surface-covering applications, comprising:a sheet materialhaving an outer surface and an opposing inner surface; a plurality ofparallely-spaced rib members extending substantially across the width ofsaid sheet material on the opposing inner surface and attached theretoby an adhesive with said sheet material being substantially flat; theadhesive bond between the sheet material and the rib members being suchthat when the structural member is bent a self detachment of the sheetmaterial from at least some of said rib members occurs allowing thesheet material to form a smooth curved shape devoid of ridges or planes;and a backing sheet between said sheet material and said plurality ofrib members, and a notch being formed between adjacent rib members, saidplurality of rib members are formed by parallely-spaced partial throughcuts in an integral core member and each of the notches extendingthrough said backing sheet toward said sheet material.
 3. A component ofa composite structural member, upon bending of the composite structuralmember a self detachment between the component and the compositestructural member occurring allowing the composite structural member toform a smooth surface curve devoid of ridges or planes, the saidcomponent comprising:a backing member in the form of a sheet oflatex-type paper; a plurality of parallely-spaced rib members attachedin non-contacting relationship with one another to one surface of saidbacking member and thereby forming said component for attachment to asheet material for forming the composite structural member; and theattachment between the rib members and the backing member is such thatwhen the component is bent a self detachment of the rib members from thebacking member occurs allowing the component to form a smooth surfacecurve devoid of ridges or planes.
 4. A component of a compositestructural member as claim d in claim 3, wherein the backing member isattached to the sheet material.
 5. A component of a composite structuralmember as claimed in claim 3, wherein the plurality of rib members areattached to the sheet material.